Added read-only file error test.

base/test/test_file_util.h

Index: base/test/test_file_util.h
diff --git a/base/test/test_file_util.h b/base/test/test_file_util.h
index ce0b30259371cd845ab90d45f592a395cb82b5da..b5407e12f5c69d2684550b3b709034d08c765aaa 100644
--- a/base/test/test_file_util.h
+++ b/base/test/test_file_util.h
@@ -11,6 +11,7 @@
 #include <string>
 
 #include "base/compiler_specific.h"
+#include "base/file_path.h"
 
 class FilePath;
 
@@ -56,6 +57,20 @@ FilePath WStringAsFilePath(const std::wstring& path);
 bool MakeFileUnreadable(const FilePath& path) WARN_UNUSED_RESULT;
 bool MakeFileUnwritable(const FilePath& path) WARN_UNUSED_RESULT;
 
+// Saves the current permissions for a path, and restores it on destruction.
+class PermissionRestorer {
+ public:
+  explicit PermissionRestorer(const FilePath& path);
+  ~PermissionRestorer();
+
+ private:
+  const FilePath path_;
+  void* info_;  // The opaque stored permission information.
+  size_t length_;  // The length of the stored permission information.
+
+  DISALLOW_COPY_AND_ASSIGN(PermissionRestorer);
+};
+
 }  // namespace file_util
 
 #endif  // BASE_TEST_TEST_FILE_UTIL_H_